Roberts R600

[Darren-UK]

The R600 is perhaps not the most interesting of subjects to waffle on about herein, but in this instance my recent work highlights only too well the problems with Roberts radios of the period and may thus be of interest to anybody starting out collecting/repairing transistor radios.

My example was obtained for ebay some time ago and I've just got round to dealing with it. I bid on this example as it was the rarer blue version and because, for some strange reason, I like its peculiar combination of silicon and germanium transistors. It is also easier to work on than the loosely similar but slightly better R700.

When I received the radio it was in a disgustingly filthy condition, didn't work on AM, barely worked on FM, was missing its turntable base and had its PP9 connector replaced with a PP3 connector. Worse still, the ferrite rod aerial was broken into three sections and these were rattling around loose in the cabinet and all wires to the aerial coils had been deliberately cut. The MW coil itself also had a damaged winding. On ebay, this radio was described fairly (just) and sold for spares/repair so I had no grumbles about that.

This weekend it was time for the R600s visit to the operating theatre. First job was to fit a proper PP9 snap and determine what was or was not happening. Next job was to clean the (filthy) chassis, wavechangers and on/off/volume pot. FM was then much better but it was intermittent and accompanied by lots of nasty crackling.

I decided to leave this for the time being and sort out the AM and aerial trouble, bearing in mind there must have been a reason the wires had all been severed and the ferrite broken into three ( the latter can only be through sheer clumsiness ). I had no suitable ferrite rod spare I could use, so decided to rebuild the original with superglue and this seemed a prudent measure at the time in case I later found the radio had been damaged beyond reasonable repair efforts. It was, of course, obvious by this time that it had been well and truly mucked around with. The damaged MW aerial coil proved a simple repair and I only lost one turn of the windings.

Refitting the repaired aerial, I next had to deal with the cut wires from the coils. I decided not, at this stage, to replace all these wires but to strip the ends and solder them together; an easy task as the wires had been cleanly cut and not shortened or even ripped out. To avoid any short circuits I slipped a piece of heatshrink tubing over each soldered joint.

Now it was time to power up and see what happened. To my surprise, I will admit, LW and MW both burst into life. However, as with FM, operation was intermittent and accompanied by lots of crackling. As this radio does not contain AFxxx transistors I began a search for other typical Roberts faults. Sure enough there was a partial s/c on the earphone socket which I cured in the usual manner by simply altering the wiring so as to bypass the socket.

This improved the situation but the intermittency still appeared, apparently at random. Time to look for dry joints and other mechanical defects. As was expected, there were no less than five dry/faulty joints on the pcb adjacent to the IF module, on two of the three on/off/volume pot tabs and one more on the pcb end of the pot's 'ground' connection.

All these dealt with, the radio then performed with no intermittence on all bands - although the tone of the radio just wasn't right regardless of the position of the tone button. I suspected an alignment problem. Leaving this for the time being, I wished to deal with some nasty crackling at the on/off/volume pot and this was especially bad when switching on and off. Some switch cleaner cured the crackling whilst adjusting the volume but the problem at on/off remained. I noticed that when switching off, the crackling continued for a couple of seconds until fading out altogether. I therefore suspected a faulty electrolytic and traced this to yet another dry joint at the + end of C16 ( a 2.2uf job, given on the service sheet as 2.5uf ). This dealt with, the crackling trouble at the pot vanished.

The radio now performed ok apart from the suspect alignment problem. Eventually I reached the stage whereby I needed to remove the label on the IF module which advises you to return any faulty module to Roberts. Not surprisingly, the service data gives no instructions re alignment of the IF module. Beneath this label and peering through the modules access holes, it was obvious the plastic-headed inductor cores had been tampered with and the label stuck back in place. Ok, so I had to realign the module with no instructions - something I'm quite good at doing so I wasn't bothered. However, I soon noticed one of the cores had a badly damaged head as if it had been screwed right down under some force. Fortunately I didn't have to open up the module; I took a 1mm diameter drill and heated up its tip, then twisted it into the plastic head of the core and applied some freezer spray to cool it and perhaps harden the plastic slightly. Using a tiny drop of switch cleaner to act as a lubricant and with fingers very crossed, I was able to unscrew and remove the damaged core and replace it with another which, as luck would have it, I found in one of my tubs of bits and pieces. This damaged core was the main cause of the alignment problem; other cores just needing slight adjustment.

That was the electronics dealt with, next the cabinet. Much of the cabinet work consisted of simply cleaning off years of accumulated muck, but two other problem were present. Firstly, some clown had damaged some of the black horizontal 'bars' from the front grille, with the ends of some totally gone ( this radio is, obviously, the later version ). A word of warning here; both Servisol and Maplins foam cleaner will damage the black grille 'bars' on these radios ..... something I discovered to my cost many years ago. Using a 12" clear perspex rule and a fine tipped permanent marker pen and good lighting, I was able to 'repair' the damage to the grille finish to an extent where it is hardly noticeable.

The second problem concerned the wooden base cover. I replaced the turntable from several spares I have, but the base itself - although it has the tag affixed with R600 on it - was too short and simply dropped out if moved slightly. I cured this by bending out the spring under one end of the cabinet slightly and affixing a strip of self adhesive felt under the chrome keeper at the cabinets other end.

The wooden ends of the cabinet were also badly faded or 'sunbleached'. These end pieces seem to be stained but not varnished ( comments anyone ? ) and some Rustins wood dye soon brought the wood back to how it should look.

That was the radio finished It still contains the superglued ferrite rod and the associated repaired wiring; I will replace this all properly one day but for the time being it's doing its job and the radio babbles away as it should do.

This was a strange case; prior to the deliberate damage to the aerial, its wiring and that inductor core, the radio was probably in working order ... so why damage it in such a fashion ? Maybe it developed a dry joint problem and a previous owner was just so clueless he ended up wrecking it - who knows. Sorry this posting is rather long and hope it's of interest to some readers.

[howard]

Hello Darren,

Thats jolly good, it looks really nice now, I rebuilt a blue R600 myself from two eBay sourced radios, I didnt have quite as many problems as you though but theyre nice radios the R600s, particularly in blue or yellow and well worth restoring and preserving.

Howard

PS: If you want an aerial for it I have one from the remaining scrap radio

[Darren-UK]

Thanks for that Howard. Re the aerial, this was one of the few component parts of the radio that had survived undamaged. When this and other Roberts models turn up, they often have a shot aerial ...... on my example it was just about everything else that was shot

I remain baffled as to how the aerial came to be broken into three; broken aerials are common on models like the R200 where people tend to lift the chassis out by holding the aerial, but not on the R600 etc.

[howard]

Hello Darren,

If you want the ferrite rod aerial, PM me.

Howard